This invention relates to a shut-down device for a diesel engine, and more particularly, relates to a device for stopping the engine by cutting fuel and/or air.
In general, the diesel engine which is driven by self ignition of a fuel with compressed heat is stopped by cutting fuel after operating a stop lever or closing a switch valve provided in an intake system to cut intake air.
Each of Japanese Utility model laid-open NOS. 1986-167436 and -171843 disclose an engine that is stopped by turning a key switch in the "accessory" mode to turn on a shut-down solenoid. The solenoid forces a control rack of an fuel injection pump to be transferred to a position where the engine is stopped.
In the above prior art, the key switch should be in the "accessory" mode until the engine stops. However, if the key switch happens to be left in the "accessory" mode after the engine stops, a battery consumes electric power excessively. This drains the battery and makes it difficult for the engine to restart.
There is an engine shut-down device employing a timer disclosed in Japanese Patent NO. 1981-1464 in order to solve the above problem. This engine shut-down device operates as follows: When a key switch is turned off in order to stop a diesel engine, a timer starts simultaneously and a solenoid control device also operates to supply an electric power to a solenoid from a power supply while the timer is operating. The solenoid actuates to cut the fuel. The engine therefore stops.
However, in this prior art, the timer needs a sufficient interval of time for the engine to stop after a fuel system is shut down. Moreover, the interval of time should be long enough to cover shut down variations of the engine. The solenoid thus continues to operate while the timer is operating even after the engine stops. This causes electric power to be excessively consumed. Accordingly, the solenoid is heated excessively even if the solenoid has a short maximum rated energizing time and there is a load on the battery.
Furthermore, if fuel feed is not shut down after the key switch is turned off due to such as mechanical malfunction of a fuel feed shut-down device so that the engine does not stop automatically, the solenoid may be applied with electric power beyond its maximum rated energizing time. The solenoid may therefore be burned out.